89 Campfire Science-Mid

Campfire Science FOCUS Question Why do people use campfires?

篝火科学焦点问题为什么人们使用篝火?

Why We Make Campfires Thousands of years ago, people made campfires. Fires protected people from predators and biting insects. They made people feel safe. The flames kept people warm and cooked raw meat. The light helped people locate family and friends in the dark. Today, electricity helps people do many of these things. People live in warm houses for protection. Electricity lights up the night. Stoves and microwaves heat food. And people connect with each other using cell phones and computers. But people still enjoy campfires. When people go camping they use fire to cook their food and keep warm. A campfire is still a good spot for friends and family to gather and tell stories.

几千年前，人们生营火。 火保护人们免受捕食者和昆虫的侵害。 他们让人们感到安全。 火焰使人们保持温暖，并煮生肉。 这种光可以帮助人们在黑暗中找到家人和朋友。 今天，电可以帮助人们做很多这样的事情。 人们住在温暖的房子里寻求保护。 电照亮了夜晚。 炉子和微波炉加热食物。 人们通过手机和电脑相互联系。 但是人们仍然喜欢篝火。 当人们去露营时，他们用火来做饭和取暖。 篝火仍然是朋友和家人聚会和讲故事的好地方。

Giving Off Energy Campfire wood has stored energy called potential energy. This type of energy is ready to be used but hasn't been yet. A ball near the edge of a table also has stored energy. It is ready to roll off but is not moving yet. The potential energy in firewood is called chemical energy. The energy in the wood is stored in its molecules. Energy itself cannot be created or destroyed. It can only change from one kind to another. When wood burns, its potential energy turns into two other kinds of energy. The change from one kind of energy to another is called a conversion (kun-VER-zhun). A conversion of energy happens when fire turns wood to ash.

释放能量营火的木头储存着一种叫做势能的能量。 这种能源已经准备好了，但还没有被使用。 靠近桌子边缘的球也储存着能量。 它准备滚下，但还没有移动。 柴火中的势能叫做化学能。 木头中的能量储存在分子中。 能量本身不能被创造或毁灭。 它只能从一种变成另一种。 当木头燃烧时，它的势能会转化成另外两种能量。 从一种能量到另一种能量的变化称为转换(kun- ver - jun)。 当火把木头变成灰烬时，就发生了能量转换。

Light and Heat Some of the potential energy in the wood is converted to light energy. That's why a fire glows! Light energy can help us feel safe on a dark night. The other type of converted energy. given off when wood burns is heat. A fire's heat is called thermal energy. This kind of energy can keep us warm and cook our food. The heat energy created by a burning campfire dissipates, or spreads out, as the fire burns. The heat warms the cool air around the fire. After a campfire has burned, the wood's chemical energy has been released, and the wood has turned to ashes.

光与热木材中的一些势能被转化为光能。 这就是为什么火会发光!光能能让我们在黑夜中感到安全。 另一种转换能量。 木头燃烧时散发出热量。 火的热量叫做热能。 这种能量可以使我们保持温暖和烹饪食物。 燃烧的营火产生的热能随着火的燃烧而消散或扩散。 热量使火周围的冷空气变暖。 篝火燃烧后，木头的化学能被释放出来，木头就变成了灰烬。

Campfire Cooking People use campfire energy to cook food through convection—the movement of heat through the air. People put marshmallows and hot dogs on sticks and hold them over a campfire. The heat energy cooks the food from a distance. Another way to cook food is through conduction. People wrap baked potatoes or kabobs in foil and place them directly into the fire's hot embers. The heat transfers directly to the food. Cooking changes the taste and texture of food. These are chemical changes that cannot be reversed.

人们利用篝火的能量通过对流(空气中的热量运动)来烹饪食物。 人们把棉花糖和热狗串在木棍上，放在篝火上烤。 热能可以远距离烹饪食物。 另一种烹饪食物的方法是通过传导。 人们把烤好的土豆或烤肉串包在锡箔纸里，直接放在火的余烬里。 热量直接传递到食物上。 烹饪会改变食物的味道和质地。 这些是无法逆转的化学变化。

Getting Ready Safety is very important when building a campfire, and you should always have an adult's help. In an open, outdoor place, clear out a large area of all leaves and sticks. Then place rocks in a big circle within the clear area to construct a fire ring. Next, collect fuel for the campfire. Thin brittle fuels such as dried grass, pine needles, and bark are called tinder. Tinder helps get the fire started. Kindling goes on top of the tinder. Kindling is made up of sticks about as thick as a pencil. Finally, place fuelwood—branches and logs—on the top.

在生营火的时候，安全是非常重要的，你应该有一个成年人的帮助。 在室外开阔的地方，清除一大片的树叶和树枝。 然后在空旷的区域内把石头围成一个大圈，形成一个火圈。 接下来，为篝火收集燃料。 薄而脆的燃料，如干草、松针和树皮被称为火绒。 Tinder可以帮你生火。 火种放在火种上。 引火是由铅笔一样粗的木棍组成的。 最后，把燃料——树枝和原木——放在顶部。